Saturable reactor

ABSTRACT

A saturable reactor including a pair of bar type cores which are respectively provided with a primary coil and a secondary coil and are arranged in parallel and a pair of magnets which are provided respectively at both ends of the cores and are arranged to contact the ends of both cores at the same time. The magnets have opposed magnetic poles of different polarity so that a biased magnetic flux flows in the cores. The primary coils are arranged so that primary magnetic fluxes are generated in the same direction with reference to the direction of the biased magnetic flux while the secondary coils are arranged so that secondary magnetic fluxes are generated in the opposite direction to each other in reference to the direction of the biased magnetic flux.

United States Patent 1151 3,701,067

Tsuhakihara Oct. 24, 1972 [$4] SATURABLE REACTOR 2,040,768 5/1936Edwards "336/1 10 X t I h 2,802,170 8/1957 Starr et al. ..336/110 x m]1;: Twmhm Kanagawa' 2,860,313 11/1953 Israel ..336/110 ['73] Assignee:Denki Onkyo Co., Ltd., Tokyo, Primary ExamingrThomas J. Kozma JapanAttorney-James E. Armstrong et al.

[22] Filed: Jan. 28, 1972 1211 Appl. No.: 221,142

[57] ABSTRACT A saturable reactor including a pair of bar type coreswhich are respectively provided with a primary coil and a secondary coiland are arranged in parallel and a pair of magnets which are providedrespectively at both ends of the cores and are arranged to contact theends of both cores at the same time. The magnets have opposed magneticpoles of different polarity so that a biased magnetic flux flows in thecores. The primary coils are arranged so that primary magnetic fluxesare generated in the same direction with reference to the direction ofthe biased magnetic flux while the secondary coils are arranged so thatsecondary magnetic fluxes are generated in the opposite direction toeach other in reference to the direction of the biased magnetic flux.

9 Claims, 5 Drawing figures [30] Foreign Application Priorlty Data Jan.28, 1971 Japan ..46/3795 [521 11.8. CI. ..336/90, 336/110, 336/132,336/155 [51] Int. Cl .1101! 21/00 [58] Field of Search ..336/110, 132,90, 155

[56] References Cited UNITED STATES PATENTS 3,157,848 11/1964 Boiten..336/110 3,390,364 6/1968 Russell ..336/1 10 2,218,711 10/1940 Hubbard..336/110 X I '1 l/l/l f I i 15 [ll/ll ljl/l 1 SATURABLE REACTORBACKGROUND OF THE INVENTION The present invention relates to a reactorfor controlling or modifying pincushion" type distortion in cathode raytube displays. it is particularly well suited for use in conjunctionwith color display tubes.

Pincushion type distortion of cathode ray tube displays has long beenrecognized. ln black-and-white displays, this type of distortion iscorrected to a considerable extent through the use of permanent magnets,which are so shaped and fixed in positions relative to the cathode as toproduce an appropriate magnetic biasing effect on the cathode ray beam.In the case of color display tubes, which are based on the use of shadowmask or similar principles, however, fixed correcting magnets cannot beused.

One approach, which has been adopted in connection with the correctionof pincushion distortion in color displays involves the modulation orvariation of one of the sweep currents in such a manner as to producethe desired results.

In the arrangement for correction of raster distortion occurring in thevertical direction (e.g., top and bottom pincushion distortion), thecyclically varying vertical scanning current must be modulated at ahigher horizontal rate, such as by adding a horizontal rate correctioncurrent alternated parabolically to the vertical deflection current.

ln the arrangement for the correction of raster distortion occurring inthe horizontal direction (e.g., side pincushion distortion), thecyclically varying horizontal scanning must be varied at a lowervertical rate, since the magnitude of a horizontal scanning current isparabolical.

It has further been suggested in the prior art that this modulation beaccomplished eiectromagnetically using a combination of magnetic andelectrical circuitry which works on the principle of magneticsaturability.

In general, nominal correction can be produced by this means. There aremany kinds of saturable reactor device and circuit connections forcorrecting pincushion distortion such as those described in U.S. Pats,No. 2,906,919, No. 3,346,765, and No. 3,444,422.

The existing reactor, as seen in the aforementioned U.S. patents, iscomposed of a core that mutually couples the two ends of three parallelyokes, a coil shuntwound on the two yokes on both sides of the core inopposite winding directions and is connected in series, and another coilwound on the center of the core. Since the vertical deflection currenthas been applied to one of the above-mentioned coils and the horizontaldeflection current has been applied to the other coil, the device hasdisadvantages as described herein.

In the manufacture of a reactor, coils arefitted to respective yokes ofan E-shaped core, and l-shaped core is coupled on the free ends of theyokes of the E- shaped core in order to magnetically couple the yokes.Using this process, the manufacturing process has been time consuming,making it unsuited to mass-production. Magnetic flux leakage has beensmall, since the yokes formed a closed magnetic path. However, sincecurrent magnetic flux density in the closed magnetic path variedmarkedly depending on the infinitesimal differences in the gaps in themagnetic path, the characteristics of individual products lostuniformity because of disparity in the gap arising in the coupled partof the E-shaped core and the I-shaped core.

Therefore, as described in U.S. Pat. No. 3,571,606, a saturable reactorcomprised of one bar type core provided with four coils has beenrecently offered. However, it is disadvantageous because this type ofthe saturable reactor has a long bar type core and handling isdifficult, for example, when attaching the reactor directly to adeflection yoke.

The present invention provides a saturable reactor which is extremelyeasily assembled to be compact and manufactured to have uniform quality.

SUMMARY The present invention provides a saturable reactor comprised ofa pair of bar type cores provided with primary coils and secondary coilsand arranged in parallel and a pair of magnets which have opposedmagnetic poles with different polarity to supply a biased magnetic fluxto the cores and are mounted so that the magnetic poles contact the endsof said cores at the same time, wherein a pair of said primary coilswhich are wound on a pair of cores generate both magnetic fluxes in thesame direction in reference to the direction of the biased magnetic fluxand a pair of secondary coils which are wound on a pair of coresgenerate the magnetic fluxes in opposite directions to each other inreference to the direction of said biased magnetic flux.

BRIEF DESCRIPTION OF THE INVENTION The present invention is illustratedin detail by the accompanying drawings whereon:

FIG, 1 is a cross sectional front view of important parts of a saturablereactor according to the present invention,

FIG. 2 is a side view of a saturable reactor according to the presentinvention,

' FIG. 3 is a cross sectional front view of important parts of saidsaturable reactor showing another embodiment,

FIG. 4 is a side view of the saturable reactor shown in FIG. 3, and

FIG. 5 is a side view of the saturable reactor illustrating anotherembodiment of the present invention.

DETAILED DESCRIPTION Referring to FIGS. 1 and 2, there is shown asaturable reactor comprised of a pair of bar type cores 1 and l whichare arranged in parallel, a pair of primary coils 2 and 2' which arewound on said cores respectively, a pair of secondary coils 3 and 3which are wound on said cores respectively and a pair of magnets 4 and4' which have opposed magnetic poles with different polarities to supplythe biased magnetic flux f to the cores and are provided at both ends ofa pair of cores. Said reactor is housed in a suitable supporting member,for example, case 5.

Said primary coils 2 and 2' are wound so as to generate both magneticfluxes in the same direction in reference to the direction of the biasedmagnetic flux. The magnetic flux are applied in the same direction as orthe reverse direction to the biased magnetic flux at the same timeaccording to the direction of the deflection current as known from theprior art.

In other words, the primary coils are wound such that when the flux ofthe first primary coil is in the same direction as the biased magneticflux of its core, the flux of the second primary coil is in the samedirection as the biased magnetic flux of its core and, conversely, whenthe flux of the first primary coil is in the opposite direction as thebiased magnetic flux of its core, the flux of the second primary coil isalso in the opposite direction as the biased magnetic flux of its core.

A pair of said secondary coils 3 and 3 are wound so as to generate themagnetic fluxes in the opposite direction to each other in reference tothe direction of the biased magnetic flux. The direction of thegenerated magnetic fluxes is reversed in accordance with the directionof the deflection current as known from the prior art.

In other words, the secondary coils are wound such that when the flux ofthe first secondary coil is in the same direction as the biased magneticflux of its core, the flux of the second secondary coil is in theopposite direction as the biased magnetic flux of its core and,conversely, when the flux of the first secondary coil is in the oppositedirection as the biased magnetic flux of its core, the flux of thesecond secondary coil is in the same direction as the biased magneticflux of its core.

When compensating the pincushion distortion appearing at the top andbottom of the raster, the primary coils are series-connected to thehorizontal deflection current source and the secondary coils areseries-connected to the vertical deflection current source.

However, the power supplies to which the primary coils and secondarycoils are to be connected and the method of connection can be determinedaccording to the purpose as known technically.

According to this embodiment, the saturable reactor is advantageousbecause the bar type core can be shortened thereby reducing length l ofthe entire reactor. It is also advantageous because one primary coil andone secondary coil can be wound on each core permitting improvedproduction efficiency by divided work. Furthermore, the winding is madeeasy and the material cost reduced because a short core can be used.

In this embodiment, magnets 4 and 4' are fixed to the cores and aremagnetized so that magnetic poles N and S are at both ends in thelengthwise direction.

However, magnets 4 and 4' can be energized in the direction of thicknessas shown in FIGS. 3 and 4 and at least one of the magnets can be disctype magnet 4, having a flux varying at a given radius from one radialto another, which is rotatable at support shaft 41 provided at thecenter of the magnet.

If the saturable reactor is thus formed, the magnetizing bias of thecores can be adjusted because the amount of the biased magnetic flux canbe changed as disc-type magnet 4 is rotated. If the magnet is made to beof the rotary type, it is desirable to fonn a knurled surface 42 on themagnet as shown in FIG. 4, thus smoothing rotation of the magnet. Themagnetizing bias of the core can be changed by rotating the disctypemagnet which is energized in the radial direction. If one or all magnetsare made to be movable magnet 4, the magnets can be moved in the radialdirection by attracting the magnets to the ends of a pair of cores asshown in FIG. 5. In this case, it is desirable to use the magnetenergized in the radial direction. The magnetizing bias of a pair ofcores 1 and 1' can be changed to the same degree or the magnetizing biasof a pair of cores can be set to different values. For example, in FIG.5, the magnetizing bias of core 1 can be reduced by shifting magneticpole S without shifting magnetic pole N.

As known from the above, it is effective for adjusting the magnetizingbias to make a pair of magnets 4 and 4 the movable type magnet.

The winding direction of said primary and secondary coils in theembodiment of FIG. 1 is different from that in the embodiment in FIG. 3.The winding direction of these coils is detemrined according to thedirection of biased magnetic flux f.

The primary coils of the saturable reactor shown in FIG. I are wound inthe same direction and the secondary coils are wound in oppositedirections, whereas the primary coils of the saturable reactor shown inFIG. 3 are wound in opposite directions and the secondary coils arewound in the same direction.

The saturable reactor according to the present invention is as describedabove. It can provide great advantages in employment in the cathode raytubes for television sets for which the demand is increasing more andmore.

Whatl claim is:

l. A saturable reactor comprised of a. a pair of bar type cores arrangedin parallel,

b. a pair of magnets having opposed magnetic poles with diflerentpolarity which contact both ends of each of said pair of cores at thesame time, said magnets being adapted to supply a biased mag netic fluxto each of said cores,

c. primary coils wound on each of said cores which are arranged togenerate magnetic fluxes in the same direction with reference to thedirection of said biased magnetic flux, and

. secondary coils wound on each of said cores which are arranged togenerate magnetic fluxes in opposite directions to each other withreference to the direction of said biased magnetic flux.

2. A saturable reactor according to claim 1, wherein at least one ofsaid magnets is rotatable.

3. A saturable reactor according to claim 2, wherein a knurled surfaceis formed on the external surface of a rotatable magnet.

4. A saturable reactor according to claim I, wherein at least one ofsaid magnets is arranged so as to be shifted in its radial direction.

5. A saturable reactor according to claim I, wherein said primary coilsare wound directly on said cores and said secondary coils are wound onsaid primary coils.

6. A saturable reactor according to claim 1, wherein said primary andsecondary coils are all wound directly on said cores.

7. A saturable reactor according to claim 1, wherein the biased magneticfluxes of each of said cores are in the same direction.

8. A saturable reactor according to claim 1, wherein the biased magneticfluxes of each of said cores are in opposite directions.

9. A saturable reactor according to claim 1, further comprising a casemeans for containing the remainder of said saturable reactor.

1. A saturable reactor comprised of a. a pair of bar type cores arrangedin parallel, b. a pair of magnets having opposed magnetic poles withdifferent polarity which contact both ends of each of said pair of coresat the same time, said magnets being adapted to supply a biased magneticflux to each of said cores, c. primary coils wound on each of said coreswhich are arranged to generate magnetic fluxes in the same directionwith reference to the direction of said biased magnetic flux, and d.secondary coils wound on each of said cores which are arranged togenerate magnetic fluxes in opposite directions to each other withreference to the direction of said biased magnetic flux.
 2. A saturablereactor according to claim 1, wherein at least one of said magnets isrotatable.
 3. A saturable reactor according to claim 2, wherein aknurled surface is formed on the external surface of a rotatable magnet.4. A saturable reactor according to claim 1, wherein at least one ofsaid magnets is arranged so as to be shifted in its radial direction. 5.A saturable reactor according to claim 1, wherein said primary coils arewound directly on said cores and said secondary coils are wound on saidprimary coils.
 6. A saturable reactor according to claim 1, wherein saidprimary and secondary coils are all wound directly on said cores.
 7. Asaturable reactor according to claim 1, wherein the biased magneticfluxes of each of said cores are in the same direction.
 8. A saturablereactor according to claim 1, wherein the biased magnetic fluxes of eachof said cores are in opposite directions.
 9. A saturable reactoraccording to claim 1, further comprising a case means for containing theremainder of said saturable reactor.